Cisco Certified Network Associate (CCNA) Practice Exam

Which type of encryption is not used for encrypting data due to its slow speed but is used for key management?

1. Symmetric Key Encryption

2. Asymmetric Key Encryption

3. Hash Function Cryptography

4. Block Cipher Encryption

The correct answer is: Asymmetric Key Encryption

The correct choice is indeed Asymmetric Key Encryption. This type of encryption employs a pair of keys, one public and one private, to facilitate secure communications. The public key can be shared openly, while the private key is kept secret. Asymmetric encryption is generally slower than symmetric encryption because of the complex mathematical operations involved in the key pair generation and encryption/decryption processes. Despite its slower performance for encrypting large volumes of data, asymmetric encryption plays a crucial role in key management. It is often used to securely exchange symmetric keys, which then are used for faster data encryption and decryption. This combination leverages the strengths of both encryption types: the speed of symmetric encryption for bulk data and the security of asymmetric encryption for the initial key exchange. In contrast, symmetric key encryption uses the same key for both encryption and decryption, making it much faster but less secure for key distribution. Hash functions are designed to validate data integrity rather than encrypt data, and block cipher encryption is a method under symmetric encryption rather than a distinct type relevant for key management alone.